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All you need to know about LASIK surgery

Like other types of refractive surgery, the LASIK procedure reshapes the cornea to enable light entering the eye to be properly focused onto the retina for clearer vision.

LASIK or “Laser-Assisted in Situ Keratomileusis,” which means using a laser underneath a corneal flap (in situ) to reshape the cornea (keratomileusis). It is the most commonly performed laser eye surgery to treat myopia (nearsightedness), hyperopia (farsightedness) and astigmatism.

How is LASIK surgery performed?

LASIKThe eye surgeon uses either a mechanical surgical tool called a microkeratome or a femtosecond laser to create a thin, circular “flap” in the cornea. The surgeon then folds back the hinged flap to access the underlying cornea and removes some corneal tissue using an excimer laser.This highly specialisd laser uses a cool ultraviolet light beam to remove (“ablate”) microscopic amounts of tissue from the cornea to reshape it so it more accurately focuses light on the retina for improved vision.For nearsighted people, the goal is to flatten the cornea; with farsighted people, a steeper cornea is desired.After the laser reshapes the cornea, the flap is then laid back in place, covering the area where the corneal tissue was removed. Then the cornea is allowed to heal naturally.Laser eye surgery requires only topical anaesthetic drops and no bandages or stitches are required.

Different types of LASIK

There are a variety of different types of lasers used in ophthalmology. All LASIK procedures are performed with a specific type of laser (excimer laser), so in one sense, all LASIK procedures are similar. However, there are a variety of different laser manufacturers, including
  • Visx
  • Wavelight
  • Alcon
  • Bausch & Lomb
  • Nidek, among others, that have all designed specific excimer lasers
Further, there are different types of laser ablations that can be performed, including conventional laser treatments, wavefront-optimised treatments and wavefront-guided treatments. Finally, a completely different type of laser (femtosecond laser) can be used instead of a mechanical microkeratome to create the LASIK (corneal) flap.

What is conventional LASIK?

LASIKConventional LASIK is the ablation pattern available on most lasers that treats directly based upon the patient’s glasses prescription, with fixed treatment parameters for each patient. This type of treatment is effective for most patients but can result in more visual deviations such as glare, halos and night vision issues than other forms of laser treatment

What is refractive error?

In the human eye, the front surface (cornea) and lens inside the eye form the eye’s ‘focusing system’ and are primarily responsible for focusing incoming light rays onto the surface of the retina. In a perfect optical system, the power of the cornea and lens are perfectly matched with the length of the eye and images are in focus; any mismatch in the system is called a refractive error and the result is a blurred image at some location.

What are the primary types of refractive error?

LASIKThere are three types of refractive errors
  1. Myopia (nearsightedness): In this condition, the mismatch in focusing power and eye length causes distant objects to be blurry and near objects to be clearer.
  2. Hyperopia (farsightedness): In this condition, the mismatch in focusing power and eye length causes near objects to be blurry and distant objects to be relatively clearer.
  3. Astigmatism: In this condition, either the corneal or lens shape is distorted, causing multiple images on the retina. This causes objects at all distances to appear blurry. Many people have a combination of either myopia or hyperopia with astigmatism.


Eyes may water and feel irritated for a few hours. It is recommended to nap and let the eyes rest. For a week, drops (antibacterial or steroidal) should be applied. Functional vision returns the night of the surgery or the day after. Follow-up visits are dispersed throughout one year at increasingly long intervals to track healing and to measure the prescription. Most patients reach 20/20 vision or better one-year out.

How do glasses or contacts improve vision in people with refractive errors?

LASIKGlasses or contact lenses are used to compensate for the eye’s refractive error by bending light rays in a way that complements the eye’s specific refractive error. In contrast, LASIK and other forms of refractive surgery are intended to correct the eye’s refractive error to reduce the need for other visual aids.

Am I too young or too old to have LASIK?

There are no hard and fast rules about the appropriate age to have LASIK. However, patients under age 18 are rarely stable enough for LASIK and older patients may begin to develop cataracts or other eye health issues that preclude them from undergoing LASIK. Again, the best way to determine these things is have a complete eye exam.

Advantages of LASIK surgery

  • LASIK is able to accurately correct most levels of myopia (nearsightedness), hyperopia (farsightedness) and astigmatism.
  • The procedure is fast, usually lasting only five to 10 minutes and is generally painless.
  • Because the laser is guided by a computer, it is very precise and results are very accurate.
  • In most cases, a single treatment will achieve the desired outcome; however, enhancements are possible if needed, even many years after the initial surgery.

Disadvantages of LASIK surgery

  • Because each patient will heal slightly differently, results may vary from patient to patient.LASIK
  • LASIK could make some aspects of your vision worse, including night vision with glare and halos.
  • LASIK may make dry-eye symptoms worse in certain individuals.
  • In rare circumstances, LASIK can make your vision worse and not correctable with regular glasses or contact lenses.

LASIK checklist

  • Know your refractive error
  • Know your treatment options
  • Know the type or laser
  • Know the risks possible with surgery
  • Know how to find the right surgeon
  • Know what to expect before, during and after surgery
Original Source: Date: Aug 18 2017Original Author: TelanganaToday